Few head to head comparisons between the Solid State Drive (SSD) and Hard Disk Drive (HDD) versions of the MacBook Air have yet been posted, but one reader (Ben Drawbaugh) did run Xbench 1.3 on the Apple Store's demo 1.8GHz SSD model. We've compiled those results along with earlier 1.6GHz HDD benchmarks in the following table.

Overall, the results of the 1.8Ghz SSD are as expected. The 1.8GHz processor gives a small boost in CPU performance. The SSD option, however, gives the most dramatic speed increases in non-sequential file reading since there is no physical drive head to move. As expected, the SSD is slightly slower at sequential file writing, but the low seek time makes up for this when performing non-sequential writes.

Typical examples of "sequential" writes and reads are when you are loading a very large file into memory or saving it out to the drive. Non-sequential reads/writes are more common when accessing a number of different small files that may be scattered across the drive (such as booting).

A traditional hard drive has a spinning platter over which the "head" moves. In order to access different files, the head may have to physically move to reach the file. The time it takes to physical move the head contributes to the seek time. SSD drives are closer to RAM and have no physical parts to move when accessing.

MacBook Air

1.6GHz HDD

1.8GHz SSD

CPU

79.98

99.61

Thread Test

148.81

134.99

Memory Test

140.42

148.00

Quartz Graphics Test

96.89

107.74

Open GL

17.26

18.27

User Interface

105.81

113.53

Disk Test

24.05

47.26

Sequential

42.21

40.82

Uncached Write

30.96 MB/s

20.83 MB/s

[4K blocks]

Uncached Write

31.19 MB/s

26.32 MB/s

[256K blocks]

Uncached Read

7.27 MB/s

7.97 MB/s

[4K blocks]

Uncached Read

30.42 MB/s

48.75 MB/s

[256K blocks]

Random

16.81

56.13

Uncached Write

0.57 MB/s

2.23 MB/sec

[4K blocks]

Uncached Write

18.35 MB/s

16.92 MB/s

[256K blocks]

Uncached Read

0.35 MB/s

7.02 MB/s

[4K blocks]

Uncached Read

13.28 MB/s

48.24 MB/s

[256K blocks]

(Larger numbers faster)

The SSD MacBook Air is also expected to offer a better battery life than the HDD version, though the magnitude of this effect is unknown. The SSD upgrade is a $999 option in the MacBook Air.

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